pie_chart.fp

varying mediump vec2 var_texcoord0;

uniform lowp sampler2D texture_sampler;

void main() {
    float x = var_texcoord0.x - 0.5;
    float y = var_texcoord0.y - 0.5;
    int angle = 20;
    float rad = radians(90 - angle);

    if(angle == 0) {
    } else if(angle > 0 && y > 0 && x > 0) {
        if(angle >= 90 || tan(rad) < (y / x)) {
            gl_FragColor = texture2D(texture_sampler, var_texcoord0.xy);
        }
    } else if(angle > 90 && x > 0 && y < 0) { 
        if(angle >= 180 || tan(rad) < (y / x)) {
            gl_FragColor = texture2D(texture_sampler, var_texcoord0.xy);
        }
    } else if(angle > 180 && x < 0 && y < 0) { 
        if(angle >= 270 || tan(rad) < (y / x)) {
            gl_FragColor = texture2D(texture_sampler, var_texcoord0.xy);
        }
    } else if(angle > 270 && x < 0 && y > 0) { 
        if(angle == 360 || tan(rad) < (y / x)) {
            gl_FragColor = texture2D(texture_sampler, var_texcoord0.xy);
        }
    }
}